OK, what fraction of LHR traffic departing to or arriving from the US consists of traffic with an origin or destination other than the UK? In other words, what fraction of traffic is transiting through or making connections at LHR to get to the US from another country or from another country to the US?

I think that it is interesting that AA is the #1 U.S. carrier to seven of the top ten international-originating markets for the United States (by frequency), as measured by number of available seats in the market:

Quoting STT757 (Reply 23):In terms of frequency I think AA is behind CO when it comes to Narita

In both frequency and capacity, AA has CO beat out of NRT. AA, this summer, will be flying a total of 42 weekly 777s from NRT to ORD, LAX, SJC, JFK, and twice daily to DFW. CO, by contrast, will fly three times daily NRT-GUM (two 762s, 1 738) and once daily each with a 777 to IAH and EWR.

AA total number of frequencies: 42 weeklyAA total number of seats: 1,422 weekly

CO total number of frequencies: 35CO total number of seats: 1,070 weekly